1. Field of the Invention
The present invention relates to a reaction liquid, a set of an ink composition and a reaction liquid, and an image recording method using the set. In particular, the present invention relates to a reaction liquid to be used for the case where printing is performed on a recording medium by using an ink composition and the reaction liquid in combination, a set of an ink composition and a reaction liquid, and an image recording method using the set.
2. Related Background Art
Ink-jet recording that enables a high-resolution and high-quality image to be printed at a high speed by means of an inexpensive apparatus is a printing method involving causing a microdroplet of an ink composition to fly and adhere to a recording medium such as paper to thereby perform printing. Various means for forming a high-quality color image have been conventionally proposed. For example, there is proposed technical means in which a black ink that thickens or aggregates by virtue of an action with a salt and a color ink containing the salt are used in combination to provide a high-quality color image having a high image density and showing no color bleeding (see, for example, Japanese Patent Application Laid-Open No. H06-106735). There is proposed another means in which an ink contains a compound that forms an insoluble complex as a result of a crosslinking reaction with a dye to improve the water resistance of an image (see, for example, Japanese Patent Application Laid-Open No. H05-194894).
There are also proposed various methods each involving preparing a liquid (reaction liquid) for obtaining a better image separately from typical ink-jet ink; causing the liquid to adhere to a recording medium prior to the ejection of a recording ink to form an image (see, for example, Japanese Patent Application Laid-Open No. H09-207424, Japanese Patent Application Laid-Open No. 2000-37942, and Japanese Patent Application Laid-Open No. H11-078211).
However, even the image recording using the combination of a reaction liquid containing a polyvalent metal ion and an ink having the reactivity with the reaction liquid typified by each of Japanese Patent Application Laid-Open No. H09-207424 and Japanese Patent Application Laid-Open No. 2000-37942 may require improvements of scratch resistance and marker resistance at a printed portion having a high image density. In addition, an invention is disclosed, in which the addition of not only a polyvalent metal ion but also a crosslinking agent (borax) for a polymer in an ink to a reaction liquid improves the water resistance of a printed article (see, for example, Japanese Patent Application Laid-Open No. H11-078211).
The inventors of the present invention have made extensive studies. As a result, they have found the following. When one attempts to prepare a conventional reaction liquid containing a polyvalent metal ion and borax serving as a crosslinking agent for polyvinyl alcohol as disclosed in Japanese Patent Application Laid-Open No. H11-078211, a precipitate may be generated to make it impossible to prepare a stable reaction liquid, probably because the polyvalent metal ion and borax are different from each other in ionicity.
There is proposed an attempt to apply a gloss treatment liquid containing no coloring material to an image provided by an ink-jet recording system to improve the gloss of the image (see, for example, Japanese Patent Application Laid-Open No. 2003-312119).